This invention relates to a circuit breaker, and more particularly, to a molded case circuit breaker accessory system.
In general the function of a circuit breaker is to electrically engage and disengage a selected circuit from an electrical power supply. This function occurs by engaging and disengaging a pair of operating contacts for each phase of the circuit breaker. The circuit breaker provides protection against persistent overcurrent conditions and against the very high currents produced by short circuits. Typically, one of each pair of the operating contacts are supported by a pivoting contact arm while the other operating contact is substantially stationary. The contact arm is pivoted by an operating mechanism such that the movable contact supported by the contact arm can be engaged and disengaged from the stationary contact.
There are two modes by which the operating mechanism for the circuit breaker can disengage the operating contacts: the circuit breaker operating handle can be used to activate the operating mechanism; or a tripping mechanism, responsive to unacceptable levels of current carried by the circuit breaker, can be used to activate the operating mechanism. For many circuit breakers, the operating handle is coupled to the operating mechanism such that when the tripping mechanism activates the operating mechanism to separate the contacts, the operating handle moves to a fault or tripped position.
To engage the operating contacts of the circuit breaker, the circuit breaker operating handle is used to activate the operating mechanism such that the movable contact(s) engage the stationary contact(s). A motor coupled to the circuit breaker operating handle can also be used to engage or disengage the operating contacts. The motor can be remotely operated.
Various accessories are used with a circuit breaker, such as alarm, auxiliary switches, and the like. The accessories are typically mounted in the circuit breaker frame and can be serviced only by removing the circuit breaker cover thereby exposing electrically live parts. Some circuit breakers provide accessory pockets dedicated to a single type of accessory, thereby preventing other accessories from being used in that pocket. Such arrangements eliminate flexibility and increase costs since a different circuit breaker with its dedicated accessories must be used for a particular purpose.
This there is a need for a molded case circuit breaker capable of using interchangeable internal accessories in the same accessory compartment in the circuit breaker cover without exposing the live electrical connections of the circuit breaker. There is also a need for a molded case circuit breaker that can be reconfigured to provide different functions without modifying the circuit breaker latching mechanism.
One embodiment of the invention relates to the molded case circuit breaker comprising a molded housing including a main breaker cover with a first terminal and a second terminal mounted in the case. The stationary contact electrically coupled to the first terminal and a movable contact electrically coupled to the second terminal is also provided. An operating mechanism having a pivoting member movable between an ON position, an OFF position and a TRIPPED position, is coupled to the movable contact. An intermediate latching mechanism is mounted in the housing and coupled to the operating mechanism. The trip unit is coupled to the movable contact and the second terminal with the trip unit in selective operative contact with the intermediate latching mechanism. The main breaker cover is provided with an accessory compartment system comprising an accessory socket formed in the main cover on either side of an opening for the pivoting member with the accessory socket in communication with the housing and configured to accept a plurality of different types of accessories. A latching protrusion is mounted in the socket for engaging the accessory. A separate accessory cover sized to cover the accessory mounted in the accessory socket is attached to the breaker cover.
Another embodiment of the present invention presents a cover for a molded case circuit breaker having an operating mechanism and an intermediate latching mechanism with the cover comprising a substantially planer member having a central opening and an accessory compartment formed in the planer member on either side of the opening with the accessory compartment configured to accept a plurality of different types of accessories and having a plurality of holes wherein a circuit breaker accessory is nested in the accessory compartment and is in contact with one of the operating mechanism and the intermediate latching mechanism.